1. Field of the Invention
The invention relates to a vehicular lamp that uses a light-emitting element as a light source.
2. Description of the Related Art
Vehicular lamps that use a light-emitting element, such as a light-emitting diode, as a light source are widely employed.
For example, Japanese Patent Application Publication No. 2005-203111 (JP-A-2005-203111) describes a vehicular lamp. The vehicular lamp includes a light-emitting element and a translucent member. The light-emitting element is arranged to face forward with respect to the lamp so that an optical axis extends in a front-rear direction of the lamp. The translucent member is arranged so as to cover the light-emitting element from its front side.
In the vehicular lamp described in JP-A-2005-203111, a center area of the translucent member, located near the optical axis, is configured to allow light that enters the translucent member from the light-emitting element to be directly emitted forward from its front surface. In addition, a peripheral area of the translucent member around the center area is configured to allow light that enters the translucent member from the light-emitting element to be internally reflected on its rear surface to form substantially parallel rays of light directed forward and then to allow the substantially parallel rays of light to be emitted forward from its front surface.
When the translucent member described in JP-A-2005-203111 is used, it is possible to improve the appearance of the lamp when the lamp is turned on and to accurately perform light distribution control while the luminous flux utilization factor of light from the light-emitting element is increased.
However, the vehicular lamp described in JP-A-2005-203111 is configured so that the peripheral area of the translucent member serves as a mortar-like light guide, so, for example, when the above vehicular lamp is applied to a vehicular lamp having a narrow vertical width as in the case of a high mount stop lamp, it is difficult to increase the luminous flux utilization factor of light from the light-emitting element.